The invention relates to a method and a device for packaging and conserving in a sterile condition a flexible hydrophilic intraocular lens which is ready to use, i.e. ready to be implanted by injection through an incision formed in the wall of a patient's eye.
Flexible intraocular lenses have the advantage of being able to be folded, allowing them to pass through incisions of small dimensions. To achieve this folding and injection of the lens into the eye, various devices have been proposed. For example, WO 9628121 and WO 9615743 propose, in the case of lenses which can be conserved dry (made of non-hydrophilic materials such as silicones), disposable injection devices comprising a folding cartridge and an injection device. The lens can be loaded into the cartridge before packaging and steam sterilization in an autoclave.
WO 9820819 also describes a packaging device for an injection kit for a non-hydrophilic lens, comprising a chamber for storing the lens in the non-folded state, and a device for transferring and folding the lens in an injector chamber. The assembly is held on a support plate itself enclosed by an envelope. In this case, too, the assembly can be sterilized.
However, such devices are not compatible with intraocular lenses called hydrophilic lenses, made of hydrophilic material(s) which need to be kept in a hydrated state for conservation.
Throughout the present text the term “hydrophilic lens” refers to any lens formed by a material such that it needs to be maintained in a liquid solution for conservation before use. Such lenses may be made, for example, of materials referred to as “hydrogel”, “acrygel” or “acrylic” (the latter term deviating from its normal meaning), which materials are PMMA (polymethylmethacrylate) and/or HEMA (hydroxymethylmethacrylate), hydrated to more than 16%, in particular between 24% and 28%. U.S. Pat. No. 4,787,904 also describes various examples of materials that may be used to produce a hydrophilic lens.
Hydrophilic lenses have the particular advantage of good biocompatibility. In particular, they are compatible with natural aqueous humor from the chemical, physical and optical (appropriate angle of contact) points of view. In addition they have high flexibility, allowing them to be folded and/or rolled to facilitate their insertion through an incision of reduced dimensions, in particular through the incision formed to introduce into the eye the material necessary for the prior surgical treatment (for example, an incision of 3 mm to 3.5 mm for ablation of the lens by phaco-emulsification). In addition they have at the same time good shape memory, so that they regain their initial functional shape after insertion into the eye.
However, the problem arising with these hydrophilic lenses is precisely that of folding and manipulating them at the moment of the surgical act. U.S. Pat. No. 4,787,904 proposes to conserve the lens in the pre-folded state in the injection device while being immersed in a conserving solution, the whole assembly being contained in a flexible packaging pocket. However, this method cannot be used in practice, for two main reasons. Firstly, a lens which has remained folded for a long period before use necessarily retains a shape memory of the folded state and therefore does not regain its perfect initial functional shape after implantation.
In addition, such packaging cannot be steam-sterilized (autoclave) after production. The liquid solution in the pocket would cause excess pressure, leading to explosion of the pocket. The production of such a package is therefore not compatible with the imperative requirements of sterilizing the lens and its packaging.
As a result, hydrophilic lenses up to now have been conserved flat in sterilized rigid flasks of conserving solution. At the moment of the surgical act, the surgeon removes the lens using a pincer, folds it (optionally with the aid of a folding device) or places it in a folding/injection cartridge or in an injector and injects it into the eye. All these manipulations are relatively complex and delicate, increasing the risk of contamination and damage to the lens.